SETX missense mutations might lead either in heterozygous or homozygous/compound heterozygous condition to ALS4 or Ataxia‐ocular apraxia 2 (AOA2)(Arning et al., 2013), which is characterized by progressive cerebellar ataxia with peripheral neuropathy, cerebellar atrophy, occasional oculomotor apraxia, and elevated alpha‐fetoprotein (AFP) serum level (Arning et al., 2013); however, insertion/deletion of relevant mutations may cause AOA2. Here, AFP is linked to cerebellar ataxia.